AppleIIbot 280 char Applesoft Demos

Background

List of Exciting 280-char BASIC programs (106 and counting)

• Part 1: Flame, Circles, Autumn, Spaceship, Nyan Cat, Double Hi-res Pattern, Double Hi-res "Raster" Bars, Box Pumpkin, Box Person, Box Apple II, 4am Bitmap, QR Code, A2 Forever, Color Picture, 80s Grid, Horizon Flyer
• Part 2: Snowflake, Christmas 2020, Plasma, C64, Sierpinski, Sierpinski Zoom, Water Drops, Rickroll, Dual Apple II/GWBASIC, Wire Spark, Tie Fighter, Amiga Ball, Floppy Rain, Pastel Scroll, 16x16 8-color images, Bresenham Lines, Cube
• Part 3: X xor Y mod 9, XOR Zoom, Hires Mod 9, Hires Sierpinski Zoom, LIST blocks, Scrolling Tokens, Window Boxes, XOR Xtravaganza, Alligator Disk, Giant Cursor, Raycaster, Stargate, Tunnel (BASIC), Tunnel (ASM), Starfield (Lores), Starburst
• Part 4: Starfield (Hires), Bresenham Circles, Hires Myst Scene, Animated Boxes, Spiderweb, Mystic Sphere, Thinking/Cracking, Fireworks, LOGO machine language, Plain Text machine language loader, LOGO Line Two Sides, Dragon Fractal, Hires Wires, Static Sweep, Pink Plasma, Purple Waves
• Part 5: Hires Moving Waves, LOGO Ocean Scene, Thick Sine, Turkey Time, Hires Doom Fire, Hires Screen Wipe, Christmas Scene, Edgarware, Cosine Effect 3, Cosine Effect 4, Orb Horror, Lemming, Rainbow Cosine, Particle Effect, Lunar Lander, Background Scroll
• Part 6: Bouncing Stars, Ooze32, Star Transition, Secret Collect, Planet Hires, Planet Lores, Box Planet, Solaris1, Solaris2, Head Asplode, Solaris4, Targeting Computer, Elite, Mystery House, Spooky Office, Gr Xor
• Part 7: Multi Scroll, Lo-res Parallax, Hi-res Parallax, Sierpinski Parallax, Shapetable Message, Gears, Lo-res Logo, Lo-res Shapetable, Hi-res Pumpkin, End of Twitter
• Part 8: Post-Twitter: Twister

The Demosplash Demo

Frequent Questions

• Q. Which is better for twitter-sized code, BASIC or assembly language?
  
  A. This is a hard call, it depends a bit on what you're trying to do. Assembly code is almost always faster. It's not necessarily smaller though. BASIC wins in a lot of cases, especially ones where you have 16-bit math, multiplies, divides, trig functions, etc.
  
  
• Q. Could you write 6502 machine code that's valid ASCII and just jump to it?
  
  A. I wasted a lot of time looking into this. It is in theory possible but very verbose so it doesn't match well with the 280 character limit. The problem is the subset of instructions you get is extremely limited, and it's hard to load useful constant/variables into registers.
  
  
• Q. Could you load your assembly language programs to the zero page and get some space savings?
  
  A. It turns out Applesoft depends on a bunch of variables scattered all over the zero page so it's hard to overwrite things without crashing Applesoft before it's done.
  
  
• Q. Could you use some sort of compression algorithm? Even just RLE?
  
  A. Maybe, but 280 bytes isn't a lot to begin with, and most things, even RLE, involve bit shifting and masking something Applesoft is not really that great at.
  
  
• Q. Are there any secret BASIC tricks left you haven't used?
  
  A. There are still a few tricks remaining. There is some deep magic you can do if you call into the Applesoft interpreter direct from assembly language. Lots of articles on this from the 1980s.
  
  Applesoft supports calls like USR and & besides CALL to call into assembly language. The most useful is & which just does a plain jump to $3F5. If you load your assembly properly you can use this to save another few characters by getting rid of the CALL768. (Also if you load your code at $3F5 you can watch it being decoded as it writes to the $400 text page).
  
  
• Q. Are you the first person to do some of these tricks?
  
  A. Probably not. The Apple II has a long, long history and I was a bit young in the 80s so not really following all the tricks in use then. I'm sure many of these things were thought up and used at some point. For example I came up with putting data in REM statements on my own, but if you do a search you can find at least one example where someone else had been doing it before me and even presented at Kansasfest/published in Juiced.GS about it back before I followed those venues.
  
  
• Q. But I've seen the REM trick on other architectures!
  
  A. As far as I know qkumba and I came up with it independent from other groups, but apparently it's some sort of optimal way to load assembly on twitter across all 6502 architectures. It's used by users of the atari bot (example) and something similar was used much earlier than us by users of the BBC micro bot (example)

Code/Tool Availability

The Future